The Internet, as it has grown considerably in size and popularity, supports a significant number and types of applications. Diverse applications, such as streaming a video, downloading music, voice-over-IP, and web-based multi-user computer games or conferences are all available to users via the Internet.
As applications become more complex and demanding, it has become a challenge to effectively deliver the applications to users while maintaining quality of service. One of the key obstacles is the limited amount of bandwidth available. Due to high bandwidth requirements and intensive computations incurred by applications, such as multimedia applications and real-time voice and video applications, traditional unicast delivery techniques may not be able to meet the transmission demands of these types of applications and is not scalable to efficiently meet the demands of a large number of service providers and users.
The challenge of effectively delivering applications to users is further exasperated with respect wireless computing devices. Public, high-speed, Internet connectivity for the wireless devices is typically achieved by connection via a wireless local area network (LAN) interface, such as 802.11x or Bluetooth, to an access point which is connected to a high speed, wired connection. It remains unlikely, however, that deployment of access points will ever realize ubiquitous or even relatively broad geographical access. Even where access points are densely deployed, seamless roaming between access points remains a technical challenge and may not serve the business interests of either access point operators, venue owners or service providers. Furthermore, where access point coverage is broad, the bandwidth of the wired connection, which is typically about 1.5 Mb/s, is limited and possibly shared among a large group of users and unlikely to significantly increase in the foreseeable future.
An increasing number of the wireless devices are equipped with a wireless WAN interface, such as a 2.50 or later generation cellular link, as well as a wireless LAN interface. These wireless devices typically access the Internet via their own cellular WAN link instead of sharing a wired connection. However, the bandwidth of the cellular connection is still relatively limited, especially with respect to the LAN interface which may exceed the WAN bandwidth by one to three orders of magnitude. Furthermore, the user may incur heavy costs when using the cellular link for an extended period of time.